Field of the Invention
The invention relates to a configuration for ink supply and ink disposal for an ink printing head, which is connected to the configuration through connecting lines.
Such ink printing heads are used both in typical office printers and in small high-speed printers. The latter are components of modern machines for printing addresses or for product labeling and will soon also be part of machines for applying postage to mail. The function of the printing heads should be assured in such a way that if at all possible no missing ink dots will occur. That is important not only for the sake of the printed image quality in general but also and in particular for security-relevant printed image data, such as the monetary value, the date and the serial number of the machine in the case of postage printing.
If missing ink dots are to be prevented, the ink supply must be reliable and as free of bubbles as possible, and the nozzles of the ink printing head must be kept clean.
In the case of the first of those purposes it is known (see German Patent DE 27 09 730 C2) for the ink connecting line to be docked on the ink container through a hollow needle. The ink container is provided with a rubber-elastic closure that is pierced by the hollow needle. That prevents both the invasion of air into the ink connecting line and an unintended escape of ink from the ink container.
In order to keep the nozzles of the ink printing head clean, ink is expelled cyclically or as needed through all of the nozzles and/or aspirated through the use of a cleaning device, and the nozzle surface of the ink printing head is wiped with a wiping lip, as is seen in German Patent DE 38 10 698 C2 and Published European Patent Application 0 285 155 A1. The ink occurring in the cleaning procedure, which is referred to below as waste ink, must be disposed of in such a way that soiling of the apparatus and its surroundings is avoided.
An ink supply device for a multicolor inkjet plotter is known (see German Patent DE 33 16 969 C2), in which on one hand the ink tank for the most frequently used kind of ink and an element that retains the ink, as waste in a receptacle, are combined in a first interchangeable unit, and on the other hand the remaining types of ink are in turn combined into a further interchangeable unit. The ink-retaining element is typically necessarily changed as well when the emptied ink tank for the most frequently used ink is replaced. The first unit is constructed essentially as a flat housing, which is subdivided into an upper chamber for receiving and retaining an ink tank of elastic material, and a lower chamber having an adsorbing substance for receiving and storing the waste tank. A pump carries the waste ink through a tube to the adsorber. The ink tank communicates with the ink printing head through a tube and through a needle. The needle serves as an outlet and is inserted into a rubber connecting piece into which an ink delivery portion of the ink tank discharges on the other end.
When the empty ink tank and the ink-saturated adsorber are removed, suitable precautions must be taken to prevent soiling.
An ink supply container for ink printing devices is also known (see German Patent DE 41 04 786 C2) that is constructed as a disposable container. The ink printing device itself operates by the negative pressure principle, in which the ink supply system has a slight negative pressure with regard to the actual writing nozzle.
In a support housing, a plurality of bags of ink are disposed one above the other. Closure devices that contain a connection piece which can lock in detent fashion in an adapted opening of the support housing are welded to the front of the bags of ink. Once again, the connection piece is closed through a seal of soft rubber or silicon. Once the filled bags of ink have been put in place, the support housing is closed by ultrasound or adhesive bonding in such a way that it is no longer possible to replace the bags of ink. When the ink runs out, accordingly the entire support housing including what it is equipped with is handled as a disposable part. The support housing can be locked in detent fashion into the printer housing. In order to prevent misconnections, guides in the form of coding blocks are mounted on the support housing and cooperate with corresponding counterparts in the detent receptacle. As a result, the connection pieces of the ink supply containers are always associated with the nozzles that expel the proper colors.
Finally, a device for monitoring the supply of electrically conducting writing fluid for ink writing devices is known (see German Patent DE 27 28 283 C3), in which the junction resistance between electrodes is measured, to enable one to detect when the ink runs out. Two depressions separated by a land are molded onto the bottom of a bottle of ink. Two electrodes that detect the liquid-specific comparison resistance are disposed in the one depression and one further electrode is disposed in the other depression.
In a supplement to the above embodiment, an ink container is also known (see Published International Patent Application WO 90/00976), in which a flexible film is secured all the way around in a liquid-tight and gas-tight manner, its size being such that it forms an adequate hollow chamber for the ink liquid and when the container is empty rests on the bottom thereof. A depression is also formed into the bottom of the known container in the region of an ink outlet opening. Two electrodes are also fitted into the bottom, spaced apart from one another.